To reduce wind flow resistance and drag on a trailer, truck, semitrailer, or other vehicle, side skirts have been used which extend downwardly from a bottom of the trailer and/or chassis toward the roadway to partially enclose the floor assembly and undercarriage.
Air flow passing under a ground vehicle imparts a drag force to the vehicle when it impinges on and flows around the vehicle undercarriage components attached to or a part of the underside of a vehicle. Side skirt systems are designed to prevent or control the flow of air from entering the undercarriage region from the side of the ground vehicle, such as a trailer of a tractor-trailer truck system, for example. Such reduction on the drag of the ground vehicle may operate to conserve fossil fuels as well as other sources of vehicle drive power for hybrid vehicles, battery-operated vehicles, and alternative fuel-based vehicles, for example.
One example of a typical side skirt system is shown in U.S. Pat. No. 8,177,286, the entirety of which is expressly incorporated by reference herein. This particular skirt system is approximately 285 inches long and 32 inches tall and is configured to span most of the distance between the landing gear of a trailer and the rear wheel assembly of a trailer in order to leave a very small gap, or space, between the landing gear and the front end of the skirt system and between the rear tires of the rear wheel assembly and the rear end of the skirt system. As noted above, conventional understanding of the operation of the skirt systems is that each operates to prevent the flow of air from entering the undercarriage region of the trailer via the side of the trailer when the trailer is in transit traveling down a highway, for example. Thus, many prior art side skirt systems were designed to span generally the entire length between the rear tires and the landing gear in order to close the space below the trailer side wall between the landing gear and the rear tires in order to prevent as much air as possible from flowing under the trailer as the trailer travels down the highway.